Dead Fish On the Lakeshore, Or Rather, 'What is That Smell?'

For the last several weeks, the shores and beaches of Lake Michigan from Chicago to Door County have been littered with little dead fish called alewife.

Though a summer die-off is an annual event, the odor and sight of thousands of decaying fish along the lakeshore is getting some attention.

Richard Benson, a staff member at Shoop Park Golf Course, has noticed.

"None of the golfers are complaining, but with the east winds a few weeks ago, it was pretty ripe for awhile," he said.

Though the reasons for this die-off are not completely understood, some understanding of the alewife and its relationship to Lake Michigan is a good starting point.

In the early 1900s, locks and canals were constructed to make possible the shipping of goods between the Great Lakes and the Atlantic. Those canals allowed fish to bypass obstacles that had previously kept them out of the Great Lakes. In 1936, a fish known as the sea lamprey found its way to Lake Michigan.

The sea lamprey is an aggressive and destructive parasitic fish that attaches itself to larger fish and literally sucks out their life-fluids. By the late 1940s, the sea lamprey devastated native predatory fish populations like lake trout.

In the absence of predators, alewives found their way through the canals and were able to establish a foothold.

In 1949, alewives arrived in Lake Michigan and with an insufficient predator base, the alewife population exploded. Not only were native fish unable to compete for the available food, but also the young native fish were fed upon by alewives.

Thankfully, hard-working biologists discovered ways to gain control of the sea lamprey population. By the mid-1960s, states bordering Lake Michigan began restocking its waters with trout and salmon. With a huge supply of alewives as a food source, the project was a huge success. Predatory fish populations rebounded and helped bring the alewife population in check.

So, why do alewives die and float up onto the beaches?

Brad Eggold, a DNR Fisheries Biologist, said the alewife is sort of a fish in the wrong body of water.

"Alewife are poorly designed for life in fresh water, so the fish are physiologically stressed and extremely sensitive," he said. "If you took 10 healthy alewife from Lake Michigan and put them in a bucket of water, they’d die instantly."

With communities along the lakeshore looking to the DNR for answers, samplings of fish are being examined.

"The first thing we noticed in the fish we collected was that there were no fat reserves, which suggests that for whatever reason, the fish have not been feeding," Eggold said. Final results of the testing won’t be known for another month, but Eggold said, "I'd be really surprised if we found anything out of the ordinary."

Some communities make an effort to clean up the decaying fish, but the fish not eaten by the gulls quickly decompose back into the soils along the lakeshore. When asked about possible health concerns Eggold replied, "To my knowledge, there's absolutely nothing to worry about."

For now, dead fish on the lakeshore are something we have to live with and Benson mirrored that sentiment.

"Shoop Park is one of the most beautiful golf courses around," he said. "If you have to put up with a little fishy smell once in awhile to enjoy this type of scenery, it’s a price worth paying."